{"segment":[{"time":24,"part":[{"title":"H\u00e3y ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"Cho c\u00e1c c\u00f4ng th\u1ee9c t\u00ednh di\u1ec7n t\u00edch h\u00ecnh qu\u1ea1t tr\u00f2n b\u00e1n k\u00ednh $R$, cung ${{n}^{o}}$. C\u00f4ng th\u1ee9c kh\u00f4ng \u0111\u00fang l\u00e0:","select":["A. $S=\\dfrac{\\pi {{R}^{2}}n}{360}$ ","B. $S=\\dfrac{\\pi Rn}{180}$ ","C. $S=\\dfrac{lR}{2}$ ","D. $S=\\dfrac{\\pi Rn}{4}.\\dfrac{R}{90}$ "],"explain":" <span class='basic_left'> Ta c\u00f3 c\u00f4ng th\u1ee9c t\u00ednh di\u1ec7n t\u00edch h\u00ecnh tr\u00f2n l\u00e0: $\\pi {{R}^{2}}$ (\u0111\u01a1n v\u1ecb di\u1ec7n t\u00edch) <br\/> $\\Rightarrow $ Di\u1ec7n t\u00edch h\u00ecnh qu\u1ea1t tr\u00f2n b\u00e1n k\u00ednh $R$, cung ${{n}^{o}}$ l\u00e0: <br\/> $S=\\dfrac{\\pi {{R}^{2}}n}{360}=\\dfrac{\\pi Rn}{4}.\\dfrac{R}{90}=\\dfrac{\\pi Rn}{180}.\\dfrac{R}{2}=\\dfrac{lR}{2}$ <br\/> Suy ra c\u00e1c \u0111\u00e1p \u00e1n A, C, D \u0111\u00fang v\u00e0 \u0111\u00e1p \u00e1n B kh\u00f4ng \u0111\u00fang. <br\/><span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 B <\/span><\/span>","column":4}]}],"id_ques":1591},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","temp":"fill_the_blank","correct":[[["9"]]],"list":[{"point":5,"width":50,"type_input":"","ques":"<span class='basic_left'> Cho \u0111\u01b0\u1eddng tr\u00f2n b\u00e1n k\u00ednh $R$ c\u00f3 di\u1ec7n t\u00edch $S$ v\u00e0 \u0111\u01b0\u1eddng tr\u00f2n b\u00e1n k\u00ednh $3R$ c\u00f3 di\u1ec7n t\u00edch $S\u2019$. Khi \u0111\u00f3 di\u1ec7n t\u00edch $S'$ g\u1ea5p m\u1ea5y l\u1ea7n di\u1ec7n t\u00edch $S$. <br\/> <b> \u00d0\u00e1p s\u1ed1: <\/b> $S' =$ _input_ $S$.","explain":" <span class='basic_left'> Di\u1ec7n t\u00edch h\u00ecnh tr\u00f2n b\u00e1n k\u00ednh $R$ l\u00e0: $S=\\pi {{R}^{2}}$ (\u0111\u01a1n v\u1ecb di\u1ec7n t\u00edch) <br\/> Di\u1ec7n t\u00edch h\u00ecnh tr\u00f2n b\u00e1n k\u00ednh $3R$ l\u00e0: $S'=\\pi .\\left( 3{{R}^{2}} \\right)=9\\pi {{R}^{2}}$ (\u0111\u01a1n v\u1ecb di\u1ec7n t\u00edch) <br\/> $\\Rightarrow S'=9S$ <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $9$ <\/span><\/span> "}]}],"id_ques":1592},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","temp":"fill_the_blank","correct":[[["14"]]],"list":[{"point":5,"width":50,"type_input":"","ques":"<span class='basic_left'> H\u00ecnh vi\u00ean ph\u00e2n l\u00e0 ph\u1ea7n h\u00ecnh tr\u00f2n gi\u1edbi h\u1ea1n b\u1edfi m\u1ed9t cung v\u00e0 d\u00e2y c\u0103ng cung \u1ea5y. H\u00e3y t\u00ednh di\u1ec7n t\u00edch h\u00ecnh vi\u00ean ph\u00e2n bi\u1ebft g\u00f3c \u1edf t\u00e2m $\\widehat{AOB}={{90}^{o}}$ v\u00e0 b\u00e1n k\u00ednh \u0111\u01b0\u1eddng tr\u00f2n l\u00e0 $7cm$. <br\/> (L\u00e0m tr\u00f2n k\u1ebft qu\u1ea3 \u0111\u1ebfn ch\u1eef s\u1ed1 th\u1eadp ph\u00e2n th\u1ee9 nh\u1ea5t) <br\/> <b> \u00d0\u00e1p s\u1ed1: <\/b> Di\u1ec7n t\u00edch h\u00ecnh vi\u00ean ph\u00e2n l\u00e0 _input_ $(cm^2)$","hint":"Di\u1ec7n t\u00edch h\u00ecnh vi\u00ean ph\u00e2n $=$ Di\u1ec7n t\u00edch qu\u1ea1t tr\u00f2n $-$ Di\u1ec7n t\u00edch tam gi\u00e1c","explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai19/lv1/img\/h937_D3.png' \/><\/center> Di\u1ec7n t\u00edch h\u00ecnh qu\u1ea1t tr\u00f2n b\u00e1n k\u00ednh $7cm$, cung tr\u00f2n $90^o$ l\u00e0: <br\/> $S=\\dfrac{\\pi {{R}^{2}}n}{360}=\\dfrac{\\pi {{.7}^{2}}.90}{360}\\approx 38,5\\,\\left( c{{m}^{2}} \\right)$ <br\/> Di\u1ec7n t\u00edch tam gi\u00e1c vu\u00f4ng $AOB$ l\u00e0: <br\/> ${{S}_{\\Delta AOB}}=\\dfrac{1}{2}OA.OB=\\dfrac{1}{2}.7.7\\approx 24,5\\,\\left( c{{m}^{2}} \\right)$ <br\/> Di\u1ec7n t\u00edch h\u00ecnh vi\u00ean ph\u00e2n l\u00e0: <br\/> $S-{S}_{\\Delta AOB} = 38,5-24,5=14\\left( c{{m}^{2}} \\right)$ <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $14$ <\/span><\/span> "}]}],"id_ques":1593},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","temp":"fill_the_blank","correct":[[["471,7"]]],"list":[{"point":5,"width":50,"type_input":"","ques":"<span class='basic_left'> H\u00ecnh v\u00e0nh kh\u0103n l\u00e0 ph\u1ea7n h\u00ecnh tr\u00f2n n\u1eb1m gi\u1eefa hai \u0111\u01b0\u1eddng tr\u00f2n \u0111\u1ed3ng t\u00e2m. T\u00ednh di\u1ec7n t\u00edch h\u00ecnh v\u00e0nh kh\u0103n khi ${{R}_{1}}=13,6cm$ v\u00e0 ${{R}_{2}}=5,9cm.$ <br\/> (L\u00e0m tr\u00f2n k\u1ebft qu\u1ea3 \u0111\u1ebfn ch\u1eef s\u1ed1 th\u1eadp ph\u00e2n th\u1ee9 nh\u1ea5t) <br\/> <b> \u00d0\u00e1p s\u1ed1:<\/b> Di\u1ec7n t\u00edch h\u00ecnh v\u00e0nh kh\u0103n l\u00e0 _input_ $(cm^2)$ ","hint":"Di\u1ec7n t\u00edch h\u00ecnh v\u00e0nh kh\u0103n b\u1eb1ng hi\u1ec7u di\u1ec7n t\u00edch c\u1ee7a h\u00ecnh tr\u00f2n l\u1edbn v\u00e0 h\u00ecnh tr\u00f2n nh\u1ecf","explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai19/lv1/img\/h937_D4.png' \/><\/center> Di\u1ec7n t\u00edch h\u00ecnh tr\u00f2n l\u1edbn l\u00e0: <br\/> ${{S}_{1}}=\\pi R_{1}^{2}=\\pi .13,{{6}^{2}}\\approx 581,1\\,\\left( c{{m}^{2}} \\right)$ <br\/> Di\u1ec7n t\u00edch h\u00ecnh tr\u00f2n nh\u1ecf l\u00e0: <br\/> ${{S}_{2}}=\\pi R_{2}^{2}=\\pi .5,{{9}^{2}}\\approx 109,4\\,\\left( c{{m}^{2}} \\right)$ <br\/> Di\u1ec7n t\u00edch h\u00ecnh v\u00e0nh kh\u0103n l\u00e0: <br\/> $S={{S}_{1}}-{{S}_{2}}=581,1-109,4=471,7\\,\\left( c{{m}^{2}} \\right)$ <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $471,7$ <\/span><\/span> "}]}],"id_ques":1594},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","temp":"fill_the_blank","correct":[[["16"],["4"]]],"list":[{"point":5,"width":50,"type_input":"","ques":"<span class='basic_left'> Cho h\u00ecnh v\u1ebd, <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai19/lv1/img\/h937_D5.png' \/><\/center> <br\/> T\u00ednh di\u1ec7n t\u00edch ph\u1ea7n in \u0111\u1eadm bi\u1ebft h\u00ecnh vu\u00f4ng c\u00f3 \u0111\u1ed9 d\u00e0i c\u1ea1nh l\u00e0 $4cm$ <br\/> <br\/> <b> \u00d0\u00e1p s\u1ed1:<\/b> Di\u1ec7n t\u00edch c\u1ea7n t\u00ecm l\u00e0 $\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} - $_input_ $\\pi (cm^2)$","explain":" <span class='basic_left'> \u0110\u01b0\u1eddng tr\u00f2n n\u1ed9i ti\u1ebfp h\u00ecnh vu\u00f4ng c\u1ea1nh $4cm$ c\u00f3 b\u00e1n k\u00ednh b\u1eb1ng $2cm$ <br\/> Di\u1ec7n t\u00edch h\u00ecnh vu\u00f4ng l\u00e0: ${{S}_{1}}={{4}^{2}}=16\\,\\left( c{{m}^{2}} \\right)$ <br\/> Di\u1ec7n t\u00edch h\u00ecnh tr\u00f2n l\u00e0: ${{S}_{2}}=\\pi {{R}^{2}}=\\pi {{.2}^{2}}=4\\pi \\,\\left( c{{m}^{2}} \\right)$ <br\/> Di\u1ec7n t\u00edch ph\u1ea7n in \u0111\u1eadm l\u00e0: $S={{S}_{1}}-{{S}_{2}}=16-4\\pi \\,\\left( c{{m}^{2}} \\right)$ <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $16$ v\u00e0 $4$ <\/span><\/span> "}]}],"id_ques":1595},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","temp":"fill_the_blank","correct":[[["2,5"],["3,8"],["13,9"],["45"],["1,39"],["1,96"]]],"list":[{"point":5,"width":50,"type_input":"","ques":"\u0110i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng trong b\u1ea3ng sau (l\u00e0m tr\u00f2n k\u1ebft qu\u1ea3 \u0111\u1ebfn ch\u1eef s\u1ed1 th\u1eadp ph\u00e2n th\u1ee9 nh\u1ea5t) <br\/> <table><tr><td>B\u00e1n k\u00ednh \u0111\u01b0\u1eddng tr\u00f2n $R$<\/td><td>$2,1 cm$<\/td><td>_input_$dm$<\/td><td>_input_$cm$<\/td><\/tr><tr><td>Di\u1ec7n t\u00edch h\u00ecnh tr\u00f2n $(S)$<\/td><td>_input_$cm^2$<\/td><td>$19,6 dm^2$<\/td><td>_input_$cm^2$<\/td><\/tr><tr><td>Di\u1ec7n t\u00edch h\u00ecnh qu\u1ea1t tr\u00f2n cung $36^o$<\/td><td>_input_$cm^2$<\/td><td>_input_$dm^2$<\/td><td>$4,5 cm^2$<\/td><\/tr><\/table>","explain":" <span class='basic_left'> Di\u1ec7n t\u00edch h\u00ecnh tr\u00f2n b\u00e1n k\u00ednh $2,1 m$ l\u00e0: $S=\\pi {{R}^{2}}=\\pi .2,{{1}^{2}}\\approx 13,9\\,\\left( {{m}^{2}} \\right)$ <br\/> Di\u1ec7n t\u00edch h\u00ecnh qu\u1ea1t tr\u00f2n b\u00e1n k\u00ednh $2,1 cm$, cung tr\u00f2n $36^o$ l\u00e0: $S=\\dfrac{\\pi {{R}^{2}}n}{360}=\\dfrac{\\pi .2,{{1}^{2}}.36}{360}\\approx 1,39\\,\\left( {{m}^{2}} \\right)$ <br\/> B\u00e1n k\u00ednh \u0111\u01b0\u1eddng tr\u00f2n c\u00f3 di\u1ec7n t\u00edch $19,6 dm^2$ l\u00e0: $R=\\sqrt{\\dfrac{S}{\\pi }}=\\sqrt{\\dfrac{19,6}{\\pi }}\\approx 2,5\\,\\left( dm \\right)$ <br\/> Di\u1ec7n t\u00edch h\u00ecnh qu\u1ea1t tr\u00f2n b\u00e1n k\u00ednh $2,5 m$, cung tr\u00f2n $36^o$ l\u00e0: $S=\\dfrac{\\pi {{R}^{2}}n}{360}=\\dfrac{\\pi .2,{{5}^{2}}.36}{360}\\approx 1,96\\,\\left( d{{m}^{2}} \\right)$ <br\/> Di\u1ec7n t\u00edch h\u00ecnh tr\u00f2n c\u00f3 di\u1ec7n t\u00edch h\u00ecnh qu\u1ea1t tr\u00f2n cung $36^o$ b\u1eb1ng $4,5 cm^2$ l\u00e0: $\\pi {{R}^{2}}=\\dfrac{360.S}{36}=\\dfrac{360.4,5}{36}=45\\,\\left( c{{m}^{2}} \\right)$ <br\/> B\u00e1n k\u00ednh \u0111\u01b0\u1eddng tr\u00f2n c\u00f3 di\u1ec7n t\u00edch $45 cm^2$ l\u00e0: $R=\\sqrt{\\dfrac{S}{\\pi }}=\\sqrt{\\dfrac{45}{\\pi }}\\approx 3,8\\,\\left( cm \\right)$ <br\/> <span class='basic_pink'> V\u1eady c\u00e1c s\u1ed1 c\u1ea7n \u0111i\u1ec1n theo th\u1ee9 t\u1ef1 t\u1eeb tr\u00e1i sang ph\u1ea3i, t\u1eeb tr\u00ean xu\u1ed1ng d\u01b0\u1edbi l\u00e0: $2,5; 3,8; 13,9; 45; 1,39; 1,96$ <\/span><\/span> "}]}],"id_ques":1596},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","temp":"fill_the_blank","correct":[[["131"],["524"],["353"]]],"list":[{"point":5,"width":50,"type_input":"","ques":"T\u00ednh di\u1ec7n t\u00edch c\u00e1c h\u00ecnh qu\u1ea1t t\u01b0\u01a1ng \u1ee9ng v\u1edbi c\u00e1c h\u00ecnh \u1ea3nh (l\u00e0m k\u1ebft qu\u1ea3 \u0111\u1ebfn ch\u1eef s\u1ed1 h\u00e0ng \u0111\u01a1n v\u1ecb) <br\/> <table><tr><td> H\u00ecnh v\u1ebd <\/td><td>Di\u1ec7n t\u00edch h\u00ecnh qu\u1ea1t<\/td><\/tr><tr><td><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai19/lv1/img\/h937_D7.1.png' \/><\/td><td>_input_$cm^2$<\/td><\/tr><tr><td><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai19/lv1/img\/h937_D7.2.png' \/><\/td><td>_input_$cm^2$<\/td><\/tr><tr><td><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai19/lv1/img\/h937_D7.3.png' \/><\/td><td>_input_$cm^2$<\/td><\/tr><\/table>","explain":" <span class='basic_left'> Di\u1ec7n t\u00edch qu\u1ea1t tr\u00f2n b\u00e1n k\u00ednh $10cm$, cung ${{150}^{o}}$ l\u00e0: <br\/> $S=\\dfrac{\\pi {{R}^{2}}n}{360}=\\dfrac{\\pi {{.10}^{2}}.150}{360}\\approx 131\\,\\left( c{{m}^{2}} \\right)$ <br\/> Di\u1ec7n t\u00edch qu\u1ea1t tr\u00f2n b\u00e1n k\u00ednh $20cm$, cung ${{150}^{o}}$ l\u00e0: <br\/> $S=\\dfrac{\\pi {{R}^{2}}n}{360}=\\dfrac{\\pi {{.20}^{2}}.150}{360}\\approx 524\\,\\left( c{{m}^{2}} \\right)$ <br\/> Di\u1ec7n t\u00edch qu\u1ea1t tr\u00f2n b\u00e1n k\u00ednh $15cm$, cung ${{180}^{o}}$ l\u00e0: <br\/> $S=\\dfrac{\\pi {{R}^{2}}n}{360}=\\dfrac{\\pi {{.15}^{2}}.180}{360}\\approx 353\\,\\left( c{{m}^{2}} \\right)$ <br\/> <span class='basic_pink'> V\u1eady c\u00e1c s\u1ed1 c\u1ea7n \u0111i\u1ec1n theo th\u1ee9 t\u1ef1 t\u1eeb tr\u00e1i sang ph\u1ea3i, t\u1eeb tr\u00ean xu\u1ed1ng d\u01b0\u1edbi l\u00e0: $131; 524; 353$ <\/span><\/span> "}]}],"id_ques":1597},{"time":24,"part":[{"title":"H\u00e3y ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang","title_trans":"\u0110\u1ec1 chung cho hai c\u00e2u","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"<span class='basic_left'> Cho tam gi\u00e1c \u0111\u1ec1u c\u1ea1nh $6cm$ n\u1ed9i ti\u1ebfp \u0111\u01b0\u1eddng tr\u00f2n $(O)$. <br\/> <b> C\u00e2u 1: <\/b> T\u00ednh di\u1ec7n t\u00edch h\u00ecnh tr\u00f2n $(O)$. ","select":["A. $18\\pi \\,\\left( c{{m}^{2}} \\right)$ ","B. $12\\pi \\,\\left( c{{m}^{2}} \\right)$ ","C. $24\\pi \\,\\left( c{{m}^{2}} \\right)$","D. $18\\sqrt{3}\\pi \\,\\left( c{{m}^{2}} \\right)$"],"explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai19/lv1/img\/h937_D8.png' \/><\/center> <br\/>Gi\u1ea3 s\u1eed $ABC$ l\u00e0 tam gi\u00e1c \u0111\u1ec1u \u0111\u00e3 cho <br\/> K\u1ebb \u0111\u01b0\u1eddng cao $AH$ $\\Rightarrow AH$ \u0111\u1ed3ng th\u1eddi l\u00e0 \u0111\u01b0\u1eddng trung tuy\u1ebfn <br\/> $\\Rightarrow BH=\\dfrac{1}{2}BC=\\dfrac{1}{2}.6=3\\,\\left( cm \\right)$ <br\/> Tam gi\u00e1c $ABC$ \u0111\u1ec1u n\u00ean $O$ l\u00e0 tr\u1ecdng t\u00e2m tam gi\u00e1c <br\/> $\\Rightarrow OA=\\dfrac{2}{3}AH$ (t\u00ednh ch\u1ea5t tr\u1ecdng t\u00e2m tam gi\u00e1c) <br\/> X\u00e9t $\\Delta AHB$ vu\u00f4ng t\u1ea1i $H$ c\u00f3: <br\/> $A{{H}^{2}}=A{{B}^{2}}-B{{H}^{2}}={{6}^{2}}-{{3}^{2}}=27$ <br\/> $\\Rightarrow AH=3\\sqrt{3}\\,\\left( cm \\right)\\Rightarrow OA=\\dfrac{2}{3}AH=2\\sqrt{3}\\,\\left( cm \\right)$ <br\/> Di\u1ec7n t\u00edch h\u00ecnh tr\u00f2n $(O)$ l\u00e0: <br\/> $S=\\pi .O{{A}^{2}}=\\pi .{{\\left( 2\\sqrt{3} \\right)}^{2}}=12\\pi \\,\\left( c{{m}^{2}} \\right)$ <br\/><span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 B <\/span><\/span>","column":4}]}],"id_ques":1598},{"time":24,"part":[{"title":"H\u00e3y ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang","title_trans":"\u0110\u1ec1 chung cho hai c\u00e2u","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":"<span class='basic_left'> Cho tam gi\u00e1c \u0111\u1ec1u c\u1ea1nh $6cm$ n\u1ed9i ti\u1ebfp \u0111\u01b0\u1eddng tr\u00f2n $(O)$. <br\/> <b> C\u00e2u 2: <\/b>T\u00ednh di\u1ec7n t\u00edch c\u00e1c h\u00ecnh vi\u00ean ph\u00e2n t\u1ea1o b\u1edfi \u0111\u01b0\u1eddng tr\u00f2n $(O)$ v\u00e0 tam gi\u00e1c \u0111\u1ec1u \u0111\u00e3 cho.","select":["A. $12\\pi -9\\sqrt{3}\\,\\left( c{{m}^{2}} \\right)$ ","B. $12-9\\sqrt{3}\\,\\left( c{{m}^{2}} \\right)$ ","C. $9\\sqrt{3}-12\\pi \\,\\left( c{{m}^{2}} \\right)$","D. $12\\pi -3\\sqrt{3}\\,\\left( c{{m}^{2}} \\right)$"],"explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai19/lv1/img\/h937_D9.png' \/><\/center> <br\/> Theo c\u00e2u 1, ta c\u00f3: ${{S}_{\\left( O \\right)}}=12\\pi \\,\\left( c{{m}^{2}} \\right);\\,AH=3\\sqrt{3}\\,\\left( cm \\right)$ <br\/> Di\u1ec7n t\u00edch tam gi\u00e1c $ABC$ l\u00e0: <br\/> ${{S}_{\\Delta ABC}}=\\dfrac{1}{2}AH.BC=\\dfrac{1}{2}.3\\sqrt{3}.6=9\\sqrt{3}\\,\\left( c{{m}^{2}} \\right)$ <br\/> T\u1ed5ng di\u1ec7n t\u00edch c\u00e1c h\u00ecnh vi\u00ean ph\u00e2n l\u00e0: <br\/> $S={{S}_{\\left( O \\right)}}-{{S}_{\\Delta ABC}}=12\\pi -9\\sqrt{3}\\,\\left( c{{m}^{2}} \\right)$ <br\/><span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 A <\/span><\/span>","column":2}]}],"id_ques":1599},{"time":24,"part":[{"title":"\u0110i\u1ec1n d\u1ea5u (<; > ; =) th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","temp":"fill_the_blank","correct":[[["="]]],"list":[{"point":5,"width":50,"type_input":"","ques":"<span class='basic_left'> Cho h\u00ecnh v\u1ebd, <br\/> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai19/lv1/img\/h937_D10.png' \/><\/center> <br\/> So s\u00e1nh hai ph\u1ea7n di\u1ec7n t\u00edch trong h\u00ecnh, bi\u1ebft $\\widehat{A}={{90}^{o}};\\,AB=AC;\\,BC=3\\sqrt{2}\\,cm.$ <br\/> <b> \u00d0\u00e1p s\u1ed1:<\/b> Di\u1ec7n t\u00edch c\u1ea7n t\u00ecm l\u00e0 $S_1$ _input_ $S_2$","explain":" <span class='basic_left'> Tam gi\u00e1c $ABC$ vu\u00f4ng c\u00e2n t\u1ea1i $A$ c\u00f3: <br\/> $AB^2 + AC^2 = BC^2$ (\u0111\u1ecbnh l\u00ed Pitago) <br\/> $\\Rightarrow AB=AC=\\sqrt{\\dfrac{B{{C}^{2}}}{2}}=\\sqrt{\\dfrac{18}{2}}=\\sqrt{9}=3\\,\\left( cm \\right)$ <br\/> Di\u1ec7n t\u00edch n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n \u0111\u01b0\u1eddng k\u00ednh $AB$ l\u00e0: <br\/> ${{S}_{1}}=\\dfrac{\\pi {{R}^{2}}}{2}=\\dfrac{\\pi .{{\\left( \\dfrac{3}{2} \\right)}^{2}}}{2}=\\dfrac{9\\pi }{8}\\,\\left( c{{m}^{2}} \\right)$ <br\/> Di\u1ec7n t\u00edch h\u00ecnh qu\u1ea1t tr\u00f2n b\u00e1n k\u00ednh $3cm$ cung $90^o$ l\u00e0: <br\/> $S=\\dfrac{\\pi R{{'}^{2}}n}{360}=\\dfrac{\\pi {{.3}^{2}}.90}{360}=\\dfrac{9\\pi }{4}\\left( c{{m}^{2}} \\right)$ <br\/> Di\u1ec7n t\u00edch ph\u1ea7n c\u00f2n l\u1ea1i l\u00e0: <br\/> ${{S}_{2}}=S-{{S}_{1}}=\\dfrac{9\\pi }{4}-\\dfrac{9\\pi }{8}=\\dfrac{9\\pi }{8}\\left( c{{m}^{2}} \\right)$ <br\/> $\\Rightarrow S_1 = S_2$ <br\/> <span class='basic_pink'> V\u1eady d\u1ea5u c\u1ea7n \u0111i\u1ec1n l\u00e0 $=$ <\/span><\/span> "}]}],"id_ques":1600},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"\u0110\u1ec1 chung cho hai c\u00e2u","temp":"fill_the_blank","correct":[[["3"]]],"list":[{"point":5,"width":50,"type_input":"","ques":"<span class='basic_left'> Cho tam gi\u00e1c $ABC$ vu\u00f4ng t\u1ea1i $A$, c\u00f3 $AB=8cm$; $AC=15cm$ ngo\u1ea1i ti\u1ebfp \u0111\u01b0\u1eddng tr\u00f2n $(O)$. <br\/> <b> C\u00e2u 1: <\/b> T\u00ednh b\u00e1n k\u00ednh c\u1ee7a $(O)$. <br\/> <br\/> <b> \u0110\u00e1p s\u1ed1: <\/b> B\u00e1n k\u00ednh c\u1ee7a $(O)$ l\u00e0 _input_ $(cm)$ ","explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai19/lv1/img\/h937_D11.png' \/><\/center> <br\/> G\u1ecdi $D; E; F$ l\u1ea7n l\u01b0\u1ee3t l\u00e0 ti\u1ebfp \u0111i\u1ec3m c\u1ee7a $(O)$ v\u00e0 c\u00e1c c\u1ea1nh $AB; AC; BC$ <br\/> Ta c\u00f3: $\\left\\{ \\begin{align} & AD=AE \\\\ & BD=BF \\\\ & CE=CF \\\\ \\end{align} \\right.$ (t\u00ednh ch\u1ea5t hai ti\u1ebfp tuy\u1ebfn c\u1eaft nhau) <br\/> Do \u0111\u00f3: $\\left\\{ \\begin{align} & AE=AC-EC=AC-CF \\\\ & AD=AB-BD=AB-BF \\\\ \\end{align} \\right.$ <br\/> Suy ra $AD+AE=AB+AC-\\left( CF+BF \\right)$ <br\/> $\\Rightarrow 2AD=AB+AC-BC$ <br\/> $\\Rightarrow AD=\\dfrac{AB+AC-BC}{2}$ <br\/> X\u00e9t $\\Delta ABC$ vu\u00f4ng t\u1ea1i $A$, ta c\u00f3: <br\/> $B{{C}^{2}}=A{{B}^{2}}+A{{C}^{2}}$ (\u0111\u1ecbnh l\u00ed Pitago) <br\/> $\\Rightarrow B{{C}^{2}}={{8}^{2}}+{{15}^{2}}=289$ <br\/> $\\Rightarrow BC=17\\,\\left( cm \\right)$ <br\/> $\\Rightarrow AD=\\dfrac{8+15-17}{2}=3\\,\\left( cm \\right)$ <br\/> D\u1ec5 d\u00e0ng ch\u1ee9ng minh $AEOD$ l\u00e0 h\u00ecnh vu\u00f4ng <br\/> B\u00e1n k\u00ednh \u0111\u01b0\u1eddng tr\u00f2n n\u1ed9i ti\u1ebfp tam gi\u00e1c $ABC$ b\u1eb1ng $3 cm.$ <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $3$ <\/span><\/span> "}]}],"id_ques":1601},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"\u0110\u1ec1 chung cho hai c\u00e2u","temp":"fill_the_blank","correct":[[["31,74"]]],"list":[{"point":5,"width":50,"type_input":"","ques":"<span class='basic_left'> Cho tam gi\u00e1c $ABC$ vu\u00f4ng t\u1ea1i $A$, c\u00f3 $AB=8cm$; $AC=15cm$ ngo\u1ea1i ti\u1ebfp \u0111\u01b0\u1eddng tr\u00f2n $(O)$. <br\/> <b> C\u00e2u 2: <\/b> T\u00ednh ph\u1ea7n di\u1ec7n t\u00edch tam gi\u00e1c n\u1eb1m ngo\u00e0i h\u00ecnh tr\u00f2n $(O)$ (l\u1ea5y gi\u00e1 tr\u1ecb c\u1ee7a $\\pi =3,14$). <br\/> <br\/> <b> \u0110\u00e1p s\u1ed1: <\/b> Di\u1ec7n t\u00edch c\u1ea7n t\u00ecm l\u00e0 _input_ $(cm^2)$","explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai19/lv1/img\/h937_D12.png' \/><\/center> <br\/> G\u1ecdi di\u1ec7n t\u00edch c\u1ea7n t\u00ednh l\u00e0 $S$ th\u00ec: $S={{S}_{\\Delta ABC}}-{{S}_{\\left( O \\right)}}$ <br\/> Ta c\u00f3: ${{S}_{\\Delta ABC}}=\\dfrac{1}{2}AB.AC=\\dfrac{1}{2}.8.15=60\\,\\left( c{{m}^{2}} \\right)$ <br\/> ${{S}_{\\left( O \\right)}}=\\pi {{R}^{2}}=\\pi {{.3}^{2}}=9\\pi \\approx 28,26\\,\\left( c{{m}^{2}} \\right)$ <br\/> $\\Rightarrow S=60-28,26=31,74\\,\\left( c{{m}^{2}} \\right)$ <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $31,74$ <\/span><\/span> "}]}],"id_ques":1602},{"time":24,"part":[{"title":"Ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"select":["A. $\\dfrac{3}{5}$","B. $\\dfrac{1}{3}$","C. $\\dfrac{1}{2}$"],"ques":" Cho h\u00ecnh v\u1ebd: <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai19/lv1/img\/h937_D13.png' \/><\/center> <br\/> Khi \u0111\u00f3 t\u1ec9 s\u1ed1 di\u1ec7n t\u00edch $\\dfrac{{{S}_{1}}}{{{S}_{2}}+{{S}_{3}}}$ l\u00e0 ?","explain":" <span class='basic_left'> Ta c\u00f3 b\u00e1n k\u00ednh c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n \u0111\u01b0\u1eddng k\u00ednh $AB$ l\u00e0 $\\dfrac{AB}{2}$ <br\/> B\u00e1n k\u00ednh c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n \u0111\u01b0\u1eddng k\u00ednh $AC$ l\u00e0 $\\dfrac{3AB}{8}$ <br\/> B\u00e1n k\u00ednh c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n \u0111\u01b0\u1eddng k\u00ednh $BC$ l\u00e0 $\\dfrac{AB}{8}$ <br\/> Di\u1ec7n t\u00edch c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n \u0111\u01b0\u1eddng k\u00ednh $AB$ l\u00e0 $S=\\pi .{{\\left( \\dfrac{AB}{2} \\right)}^{2}}=\\dfrac{\\pi .A{{B}^{2}}}{4}$ (\u0111\u01a1n v\u1ecb di\u1ec7n t\u00edch) <br\/> Di\u1ec7n t\u00edch c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n \u0111\u01b0\u1eddng k\u00ednh $AC$ l\u00e0 ${{S}_{2}}=\\pi .{{\\left( \\dfrac{3AB}{8} \\right)}^{2}}=\\dfrac{9.\\pi .A{{B}^{2}}}{64}$ (\u0111\u01a1n v\u1ecb di\u1ec7n t\u00edch) <br\/> Di\u1ec7n t\u00edch c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n \u0111\u01b0\u1eddng k\u00ednh $BC$ l\u00e0 ${{S}_{3}}=\\pi .{{\\left( \\dfrac{AB}{8} \\right)}^{2}}=\\dfrac{\\pi A{{B}^{2}}}{64}$ (\u0111\u01a1n v\u1ecb di\u1ec7n t\u00edch) <br\/> $\\Rightarrow {{S}_{1}}=S-{{S}_{2}}-{{S}_{3}}=\\dfrac{\\pi .A{{B}^{2}}}{4}-\\dfrac{9\\pi .A{{B}^{2}}}{64}-\\dfrac{\\pi .A{{B}^{2}}}{64}=\\dfrac{3.\\pi A{{B}^{2}}}{32}$ (\u0111\u01a1n v\u1ecb di\u1ec7n t\u00edch) <br\/> ${{S}_{2}}+{{S}_{3}}=\\dfrac{9.\\pi .A{{B}^{2}}}{64}+\\dfrac{\\pi .A{{B}^{2}}}{64}=\\dfrac{5.\\pi .A{{B}^{2}}}{32}$ (\u0111\u01a1n v\u1ecb di\u1ec7n t\u00edch) <br\/> $\\Rightarrow \\dfrac{{{S}_{1}}}{{{S}_{2}}+{{S}_{3}}}=\\dfrac{3.\\pi .A{{B}^{2}}}{32}:\\dfrac{5.\\pi .A{{B}^{2}}}{32}=\\dfrac{3}{5}$<\/span> "}]}],"id_ques":1603},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["16"],["4"]]],"list":[{"point":5,"width":50,"type_input":"","ques":" Cho h\u00ecnh v\u1ebd: <br\/> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai19/lv1/img\/h937_D14.png' \/><\/center> <br\/> Trong \u0111\u00f3 $ABCD$ l\u00e0 h\u00ecnh vu\u00f4ng c\u1ea1nh $4cm$. Khi \u0111\u00f3, di\u1ec7n t\u00edch $S$ l\u00e0 _input_ $-$ _input_ $\\pi (cm^2)$","explain":" <span class='basic_left'> Nh\u1eadn th\u1ea5y b\u1ed1n h\u00ecnh qu\u1ea1t t\u1ea1o th\u00e0nh m\u1ed9t h\u00ecnh tr\u00f2n b\u00e1n k\u00ednh $2cm$ <br\/> Di\u1ec7n t\u00edch h\u00ecnh vu\u00f4ng $ABCD$ l\u00e0: ${{S}_{ABCD}}={{4}^{2}}=16\\,\\left( c{{m}^{2}} \\right)$ <br\/> Di\u1ec7n t\u00edch h\u00ecnh tr\u00f2n b\u00e1n k\u00ednh $2cm$ l\u00e0: $\\pi {{.2}^{2}}=4\\pi \\,\\left( c{{m}^{2}} \\right)$ <br\/> $\\Rightarrow S=16-4\\pi \\,\\left( c{{m}^{2}} \\right)$ <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $16$ v\u00e0 $4$ <\/span><\/span> "}]}],"id_ques":1604},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["16"]]],"list":[{"point":5,"width":50,"type_input":"","ques":" Di\u1ec7n t\u00edch h\u00ecnh tr\u00f2n ngo\u1ea1i ti\u1ebfp tam gi\u00e1c c\u00e2n $ABC$ c\u00f3 $\\widehat{A}={{120}^{o}};\\,AB=AC=4cm$ l\u00e0 _input_ $\\pi\\,(cm^2)$","explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai19/lv1/img\/h937_D15.png' \/><\/center> <br\/> G\u1ecdi $O$ l\u00e0 t\u00e2m \u0111\u01b0\u1eddng tr\u00f2n ngo\u1ea1i ti\u1ebfp tam gi\u00e1c $ABC$ <br\/> X\u00e9t $\\Delta ABC$ c\u00e2n t\u1ea1i $A$ c\u00f3: <br\/> $\\widehat{A}={{120}^{o}}\\Rightarrow \\widehat{ACB}=\\widehat{ABC}={{30}^{o}}$ <br\/> $\\Rightarrow \\widehat{AOB}={{60}^{o}}$ (g\u00f3c \u1edf t\u00e2m v\u00e0 g\u00f3c n\u1ed9i ti\u1ebfp c\u00f9ng ch\u1eafn m\u1ed9t cung) <br\/> M\u00e0 $OA=OB$ $\\Rightarrow \\Delta OAB$ \u0111\u1ec1u <br\/> $\\Rightarrow OA=AB=4\\,(cm)$ <br\/> $\\Rightarrow {{S}_{\\left( O \\right)}}=\\pi .O{{A}^{2}}=\\pi {{.4}^{2}}=16\\pi \\,\\left( c{{m}^{2}} \\right)$. <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $16$ <\/span><\/span> "}]}],"id_ques":1605},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["5929"]]],"list":[{"point":5,"width":50,"type_input":"","ques":"<span class='basic_left'> M\u1ed9t thi\u1ebft di\u1ec7n c\u1eaft ngang m\u1ed9t th\u00e2n c\u00e2y c\u00f3 chu vi \u0111o \u0111\u01b0\u1ee3c $154cm$. T\u00ednh di\u1ec7n t\u00edch thi\u1ebft di\u1ec7n \u0111\u00f3 (coi thi\u1ebft di\u1ec7n nh\u01b0 h\u00ecnh tr\u00f2n). <br\/> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai19/lv1/img\/h937_D16.png' \/><\/center> <br\/> <b> \u0110\u00e1p s\u1ed1: <\/b> Di\u1ec7n t\u00edch thi\u1ebft di\u1ec7n l\u00e0 $\\dfrac{\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}}{\\pi} \\,(cm^2)$","explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai19/lv1/img\/h937_D16.png' \/><\/center> <br\/> B\u00e1n k\u00ednh c\u1ee7a thi\u1ebft di\u1ec7n l\u00e0: $R=\\dfrac{154}{2\\pi }=\\dfrac{77}{\\pi }\\,\\left( cm \\right)$ <br\/> Di\u1ec7n t\u00edch thi\u1ebft di\u1ec7n l\u00e0: $S=\\pi {{R}^{2}}=\\pi .{{\\left( \\dfrac{77}{\\pi } \\right)}^{2}}=\\dfrac{5929}{\\pi }\\,\\left( c{{m}^{2}} \\right)$ <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $5929$ <\/span><\/span> "}]}],"id_ques":1606},{"time":24,"part":[{"title":"Ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"select":["A. $\\dfrac{27}{2}$","B. $\\dfrac{25}{3}$","C. $\\dfrac{22}{5}$"],"ques":" Cho h\u00ecnh v\u1ebd: <br\/> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai19/lv1/img\/h937_D17.png' \/><\/center> <br\/> Bi\u1ebft $AE = 12cm$; $AB=BC=CD=DE$. T\u00ednh di\u1ec7n t\u00edch gi\u1edbi h\u1ea1n b\u1edfi n\u0103m n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n. <br\/> <b> \u0110\u00e1p s\u1ed1: <\/b> Di\u1ec7n t\u00edch c\u1ea7n t\u00ecm l\u00e0 ?$\\pi \\,(cm^2)$","explain":" <span class='basic_left'> Do $AE=12cm\\Rightarrow AB=BC=CD=DE=3cm$ <br\/> Di\u1ec7n t\u00edch n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n \u0111\u01b0\u1eddng k\u00ednh $AE$ l\u00e0: <br\/> ${{S}_{1}}=\\dfrac{1}{2}.\\pi {{\\left( \\dfrac{AE}{2} \\right)}^{2}}=\\dfrac{1}{2}.\\pi {{.6}^{2}}=18\\pi \\,\\left( c{{m}^{2}} \\right)$ <br\/> Di\u1ec7n t\u00edch b\u1ed1n n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n nh\u1ecf l\u00e0: <br\/> ${{S}_{2}}=4.\\dfrac{1}{2}.\\pi .{{\\left( \\dfrac{AB}{2} \\right)}^{2}}=4.\\dfrac{1}{2}.\\pi .{{\\left( \\dfrac{3}{2} \\right)}^{2}}=\\dfrac{9}{2}\\pi \\,\\left( c{{m}^{2}} \\right)$ <br\/> Di\u1ec7n t\u00edch c\u1ea7n t\u00ecm l\u00e0: <br\/> $S={{S}_{1}}-{{S}_{2}}=18\\pi -\\dfrac{9}{2}\\pi =\\dfrac{27}{2}\\pi \\,\\left( c{{m}^{2}} \\right)$ <\/span> "}]}],"id_ques":1607},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["80"]]],"list":[{"point":5,"width":50,"type_input":"","ques":" <span class='basic_left'> Cho n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n t\u00e2m $(O)$ \u0111\u01b0\u1eddng k\u00ednh $AB$. Tr\u00ean c\u00f9ng m\u1eb7t ph\u1eb3ng ch\u1ee9a n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n $(O)$, v\u1ebd \u0111\u01b0\u1eddng tr\u00f2n $(O\u2019)$ \u0111\u01b0\u1eddng k\u00ednh $AC$ sao cho $AB=3AC$. Di\u1ec7n t\u00edch n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n $(O)$ l\u00e0 $90$ \u0111\u01a1n v\u1ecb di\u1ec7n t\u00edch th\u00ec di\u1ec7n t\u00edch ph\u1ea7n \u0111\u01b0\u1ee3c gi\u1edbi h\u1ea1n b\u1edfi hai n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n l\u00e0 _input_ (\u0111\u01a1n v\u1ecb di\u1ec7n t\u00edch)","explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai19/lv1/img\/h937_D18.png' \/><\/center> G\u1ecdi ${{S}_{1}}$ l\u00e0 di\u1ec7n t\u00edch n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n $\\left( O \\right)$ $\\Rightarrow {{S}_{1}}=90$ (\u0111\u01a1n v\u1ecb di\u1ec7n t\u00edch) <br\/> ${{S}_{2}}$ l\u00e0 di\u1ec7n t\u00edch n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n $\\left( O' \\right)$ v\u00e0 $S$ l\u00e0 di\u1ec7n t\u00edch c\u1ea7n t\u00ecm <br\/> Ta c\u00f3: $AB=3AC\\Rightarrow \\dfrac{AB}{2}=\\dfrac{3AC}{2}\\Rightarrow OA=3O'A$ <br\/> $\\Rightarrow \\dfrac{\\pi O{{A}^{2}}}{2}=\\dfrac{\\pi {{\\left( 3O'A \\right)}^{2}}}{2}\\Rightarrow {{S}_{1}}=\\dfrac{9.\\pi O'{{A}^{2}}}{2}=9.{{S}_{2}}$ <br\/> $\\Rightarrow {{S}_{2}}=\\dfrac{{{S}_{1}}}{9}=\\dfrac{90}{9}=10$ (\u0111\u01a1n v\u1ecb di\u1ec7n t\u00edch) <br\/> Di\u1ec7n t\u00edch c\u1ea7n t\u00ecm l\u00e0: $S={{S}_{1}}-{{S}_{2}}=90-10=80$ (\u0111\u01a1n v\u1ecb di\u1ec7n t\u00edch)<br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $80$ <\/span><\/span> "}]}],"id_ques":1608},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["66"]]],"list":[{"point":5,"width":50,"type_input":"","ques":"Cho h\u00ecnh v\u1ebd sau, <br\/> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai19/lv1/img\/h937_D19.png' \/><\/center> <br\/> Bi\u1ebft $AB=14,BC=8,\\pi =\\dfrac{22}{7}.$ Khi \u0111\u00f3, di\u1ec7n t\u00edch mi\u1ec1n t\u00f4 \u0111\u1eadm l\u00e0 _input_ (\u0111\u01a1n v\u1ecb di\u1ec7n t\u00edch)","explain":" <span class='basic_left'> Ta c\u00f3: $AC=AB-BC=14-8=6$ <br\/> Di\u1ec7n t\u00edch n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n \u0111\u01b0\u1eddng k\u00ednh $AB$ l\u00e0: $\\dfrac{\\pi {{\\left( \\dfrac{AB}{2} \\right)}^{2}}}{2}=\\dfrac{\\dfrac{22}{7}{{.7}^{2}}}{2}=77$ (\u0111\u01a1n v\u1ecb di\u1ec7n t\u00edch) <br\/> Di\u1ec7n t\u00edch n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n \u0111\u01b0\u1eddng k\u00ednh $BC$ l\u00e0: $\\dfrac{\\pi {{\\left( \\dfrac{BC}{2} \\right)}^{2}}}{2}=\\dfrac{\\dfrac{22}{7}{{.4}^{2}}}{2}=\\dfrac{176}{7}$ (\u0111\u01a1n v\u1ecb di\u1ec7n t\u00edch) <br\/> Di\u1ec7n t\u00edch n\u1eeda \u0111\u01b0\u1eddng tr\u00f2n \u0111\u01b0\u1eddng k\u00ednh $AC$ l\u00e0: $\\dfrac{\\pi {{\\left( \\dfrac{AC}{2} \\right)}^{2}}}{2}=\\dfrac{\\dfrac{22}{7}{{.3}^{2}}}{2}=\\dfrac{99}{7}$ (\u0111\u01a1n v\u1ecb di\u1ec7n t\u00edch) <br\/> Di\u1ec7n t\u00edch c\u1ea7n t\u00ecm l\u00e0: $S=77-\\dfrac{176}{7}+\\dfrac{99}{7}=66$ (\u0111\u01a1n v\u1ecb di\u1ec7n t\u00edch) <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $66$ <\/span><\/span> "}]}],"id_ques":1609},{"time":24,"part":[{"title":"H\u00e3y ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":5,"ques":"<span class='basic_left'> Cho hai \u0111\u01b0\u1eddng tr\u00f2n \u0111\u1ed3ng t\u00e2m $\\left( O;\\,5cm \\right)$ v\u00e0 $\\left( O';\\,3cm \\right)$. Tr\u00ean $(O)$ l\u1ea5y hai \u0111i\u1ec3m $A$ v\u00e0 $B$ sao cho $\\widehat{AOB}={{60}^{o}}.$ \u0110o\u1ea1n th\u1eb3ng $OA; OB$ c\u1eaft $(O\u2019)$ l\u1ea7n l\u01b0\u1ee3t t\u1ea1i $C$ v\u00e0 $D$. T\u00ednh di\u1ec7n t\u00edch h\u00ecnh v\u00e0nh kh\u0103n \u0111\u01b0\u1ee3c gi\u1edbi h\u1ea1n b\u1edfi hai cung nh\u1ecf $AB$ v\u00e0 $CD$. ","select":["A. $16\\pi \\,\\left( c{{m}^{2}} \\right)$ ","B. $12\\pi \\,\\left( c{{m}^{2}} \\right)$ ","C. $\\dfrac{8\\pi }{5}\\,\\left( c{{m}^{2}} \\right)$","D. $\\dfrac{8\\pi }{3}\\,\\left( c{{m}^{2}} \\right)$"],"explain":" <span class='basic_left'> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/hinhhoc/bai19/lv1/img\/h937_D20.png' \/><\/center> <br\/> Di\u1ec7n t\u00edch h\u00ecnh qu\u1ea1t b\u00e1n k\u00ednh $5cm$ cung $60^o$ l\u00e0: $\\dfrac{\\pi .O{{A}^{2}}.60}{360}=\\dfrac{25.\\pi }{6}\\,\\left( c{{m}^{2}} \\right)$ <br\/> Di\u1ec7n t\u00edch h\u00ecnh qu\u1ea1t b\u00e1n k\u00ednh $3cm$ cung $60^o$ l\u00e0: $\\dfrac{\\pi .O{{C}^{2}}.60}{360}=\\dfrac{3.\\pi }{2}\\,\\left( c{{m}^{2}} \\right)$ <br\/> Di\u1ec7n t\u00edch c\u1ea7n t\u00ecm l\u00e0: $S=\\dfrac{25.\\pi }{6}-\\dfrac{3.\\pi }{2}=\\dfrac{8.\\pi }{3}\\,\\left( c{{m}^{2}} \\right)$ <br\/><span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 D <\/span><\/span>","column":4}]}],"id_ques":1610}],"lesson":{"save":0,"level":1}}